For Juniper Networks EX4300-MP Series Switches, when a mge interface receives MAC pause frames, the mge interface PHY flag will flip from 0x17(allow rx and tx) to 0x7 (block rx and tx). This issue is noticed only on mge interfaces and in older PHY version - 5d47.37a.47.305 which can be found in show chassis firmware detail. While the issue is occurring, the kernel and BCM counters will show the actual traffic, however, they will get dropped in the PHY.

How to confirm the PHY is corrupted:

Non-Working-State:

user@switch>request pfe execute target fpc0 command "test tvp phy aq read 0 30 3 0xC484"
SENT: Ukern command: test tvp phy aq read 0 30 3 0xC484 >> 30 > mge-0/0/30
3.0xc484 = 0x7   >>>> tx and rx blocked

Working state:

user@switch>request pfe execute target fpc0 command "test tvp phy aq read 0 30 3 0xC484"
SENT: Ukern command: test tvp phy aq read 0 30 3 0xC484
3.0xc484 = 0x17   >>>> tx and rx allowed

Upgrade the PHY version to 5d47.4e7.b7.307.

Please contact JTAC for PHY upgrade instructions.

[EX4300-48MP] mge interface stop forwarding traffic (juniper.net)